Method and apparatus for receiving sustained wave signals



A; N. GOLDSMITH. METHOD AND APPARATUS FOR RECEIVING SUSTAINED WAVE SIGNALS.

APPLICATION FILED JULY 28,1919.

Patented Oct. 17, 1922.

4 SHEETS SHEET 1.

A. N. GOLDSMITH.

METHOD AND APPARATUS FOR RECEIVING SUSTAINED WAVE SIGNALS.

APPLICATION FILED JULY 28.19I9.

Patented Oct. 17, 1922.

4 SHEETSSHEET 2.

A; A'ITNEY A. N. GOLDSMITH.

METHOD AND APPARATUS FOR RECEIVING SUSTAINED WAVE SIGNALS. APPLICATION man JULY 28. 1919.

1,432,455, Patenwi Oct. 17, 11922.

4 SHEETSSHEET 3.

BY 7% I /4 l/ A. N. GOLDSMITH.

METHOD AND APPARATUS FOR RECEIVING SUSTAINED WAVE SIGNALS.

APPLICATION FILED JULY 28,1919.

Patented 00t- ]I7, 1922.

SHEET 4.

4 SHEETS INVENTOR Patented Get. 117, 1922.

PATENT @FFECCE.

UNITED STATE ALFRED NORTON GOLDSMITH, OF NE)? YORK, N. Y., ASSIGNOR, BY MESNE ASSIGN- MENTS, TO RADIO CORPORATION OF AMERICA, A CORPORATION OF DELAWARE.

METHOD 'AND APPARATUS FOR RECEIVING SUSTAINED WAVE SIGNALS.

Application filed July 28,

T 0 all whom it may concern.

Be it known that I, ALFRED N; GOLDSMITH. a citizen of the United States. and a IQSltlQRl" of the borough of Manhattan, city, county, and State of New York, have invented certain new and useful Improvements in Methods and Apparatus for Receiving Sustained Vave Signals, of which the following is a specification, accompanied by drawings.

This invention relates to radio signaling, but more particularly to a new method and apparatus for receiving sustained wave signals.

The usual methods heretofore practiced for receiving sustained wave signals, involve beat reception, or else are based upon variations of inductance, capacity or coupling in the receiving set at audio frequencies by means of rotating elements. Vith the exception of beat reception, for which careful adjustments are required, particularly at short wave lengths, together with unusually complete constancy of transmitting frequency, the other methods referred to suffer from one or more of the following principal objections:

1. The tone produced is too low, because of the difiiculty of obtaining the required frequency with mechanically rotating parts. In order to obtain a frequency of 500 cycles per second, such rotating elements generally have had to rotate 500 times per second, which is a difficult mechanical problem to solve.

2. Unreliability of contact to a rotating element has been a serious disadvantage. Unless a condenser connection is made to the. rotating elements, (and this is very difficult at the longer wave lengths, where a large rapidly spinning condenser is required) a sliding contact must be used, which is completely unreliable so far as very minute radio frequency currents are concerned.

3. Interference from undesired stations has been serious. In methods using-a variable condenser or a variable inductance. the primary and secondary circuits are detuncd many times per second, thus rendering them responsive to undesired interfering signals on other wave lengths.

4. Double resonance tuning has interferred with operation. Since resonance can be obtained with two possible adjustments of the slowly variable elements, as capacity or inductance,there are always two points on the 1919. Serial No. 313,691.

condenser or inductance scale at which signals are heard, which is an objectionable effect similar to that obtained from closely coupled spark transmitters, and on long waves this effect is marked.

5. In addition there has always been great difliculty in shielding the receiving set a 'ainst induction from the motor driving the rotating element, and other disadvantages could be mentioned.

The object of my invention' is to produce a method and apparatus for receiving sustained wave signals which does not operate with heat reception and yet has none of the disadvantages mentioned in connection with the other methods referred to.

My improved method and apparatus, although utilizing a rotating element or elements in one of the preferred forms shown. enables me to obtain any desired audible tone in the receiver, avoids contacts with moving parts, eliminates interference from undesired stations, avoids double resonance tuning and overcomes induction from the motor driving the rotating element.

In accordance with my invention, I modulate the incoming energy periodically or intermittently at a rate capable of producing an audio frequency cycle and an audible tone in the receiver. In one of the preferred forms of my invention, I modulate the energy by varying the mutual inductance between the coupling coils acting as a transformer in the receiver circuits and thus produce an audible tone in the receiver.

The modulation may be effected for instance, by inserting and withdrawing a conducting shield between the primary and sec ondary coils acting as a transformer to transfer energy from one circuit of a receiver to another, as from the primary to the secondary circuit. At the instant that the shield is between the coupling coils, and of a size and area to shield or cover the aperture of both coils, the secondary current is practically zero, and upon withdrawing the shield, the coupling between the coils is again established, and the amplitude of the secondary I relation to the devices for carrying out the method as claimed herein, may vary without departing from the spirit of my invention.

The intermittently inserted shield may or may not be grounded as desired, and should preferably be of good conducting material, for example, copper or silver, but not necessarily a metal. The dimensions of the shield should be of substantially the same order of magnitude as the aperture of the primary and secondary coils.

Under these conditions the shield acts as an electro-magnetic shield, since it is a short circuited' secondary of low resistance, and practically no electro-magnetic induction can occur between the primary and secondary coils when the shield is properly proportioned and in position between the coils. It is also an electro-static shield, because it acts as an equipotential surface on a conductor of large capacity, (being part of a fairly large element which may be rotating) or as a grounded conductor. In either case electro-static or capacity induction is much reduced.

Preferred forms of apparatus operating in accordance with my method are shown in the accompanying drawings in which Fig. 1 is a diagrammatic representation of circuits and apparatus for carrying out the invention; 1

, Fig. 2 is a detail side view of a toothed disk or rotator of the modulator shown in Fig. 1;

Figs. 3, 4, and 5 are detail views partly broken away showing modified forms of teeth for the modulator disk;

Fig. 6 is a diagrammatic representation of modified circuits;

Fig. 7 is a detail side view of the toothed disk of Fig. 6 showing the relative arrangement and spacing olf the coupling coils with Figs. 8, 9, 10, and 11 are diagrammatic views of modified circuits showing different locations of the modulator in the receiver circuits;

Fig. 12 is a diagrammatic view of another modification;

Fig. 13 is a detail side view of the disk of Fig. 12 showing the relative spacing of the cou ling coils; and

igs. 14 to 21 inclusive are detail views showing modified forms of modulator elements which may" be used instead of, a toothed disk.

Referring to the drawings and at first more particularly to Figs. 1 and 2; A repre sents the antenna of a receiving station,

grounded at B and having the variable loading coil C and the primary coupling coil D. The secondary circuit E includes the second ary coupling coil F, the variable inductance G, the variable tuning condenser H, detector J and telephones K.

The coupling coils D andF as shown are preferably so shaped as to be of long oblong cross-section, as this is a. vpractical working arrangement, although they may be of any desired shape and construction, provided the intermittently inserted shield has a shape and form which is appropriately chosen. The shield'of the modulator which is operatively connected to be periodically or intermittently interposed between the coils D and F, is shown in this instance as a toothed copper disk L, which may or may not be grounded as shown at O in Fig. 6. The disk L is conveniently mounted on the shaft P of a suitable motor Q, in such position that the teeth It pass between the coils D and F and these teeth are preferably of proper size and dimensions to substan- I tially completely cover the aperture of the coils when registering therewith as shown in side view in Fig. 2. The motor driving the disk may conveniently have a variable speed.

As the modulator disk L is rotated between the coupling coils D and F, the induction between the coils is periodically varied,

in effect coupling and decoupling the coils. By choosing a pro er number of teeth on the disk or rotator and a suitable running speed, a note of any desired pitch may be obtained in the telephones K. In one preferred form of the apparatus, I have used a rotator L of copper, 12 inches in diameter, having 12 teeth and driven at a speed of 3600 revolutions per minute.

The pitch of the tone produced in the receiver telephones K is obviously controllable at will by varying either the speedof the motor or the number of teeth on the rotator. The quality of the tone is also variable at will. Withthe teeth shown in Fig. 2 a. substantially pure note is obtained. In Fig. 3 is shown a form of tooth for the disk L whereby a note corresponding to iiat top audio frequency tone can be obtained. With Fig. 4 a note corresponding to peaked top audio frequency tone 18 obtained and with Fig. 5 a mixed audio frequency tone is obtained.

, It might be expected that a certain amount of induction from the motor Q would cause a hum in the receiving set, but this effect can be substantially completely avoided by enclosing the motor Q, and modulator in a closed and grounded copper box indicated diagrammatically at S, or by using an insulating shaft P or insulating shaft coupling P for the rotator L, or by placing the modulator at a point in the circuits where the major portlon of the total desired amplification has already been secured, which latter feature will be referred to {11101-9 fully in connection with Figs. 8

Although I have used comparatively large inductances in the modulator without evidence of double wave secondary tuning being produced, the preferable arrangement is that shown in Fig. 1. The loose antennato-sccondary coupling forms a part of the modulator, but the major portions of both the antenna circuit inductance C and the secondary circuit inductance G, are external to the modulator and therefore invariable so far as audio frequency modulations are concerned.

The effect of the introduction of a copper tooth into the magnetic field of the modulator coils D and F is to reduce their inductance. The relative unimportance of the modulator coils as compared to the total inductance in their circuits, and the small variation in their inductance causedby the introduction of a tooth into the field for both, renders the detuning effect caused by modulation negligible.

Special means may, if desired,-be provided for insuring that the total inductance of the circuits remains unchanged, as indicated in the modification shown in Figs. 6 and 7. In these figures, the coils D and F indicated in this instance diagrammatically, form as before, the modulator coupling be tween the antenna circuit A and the secondary circuit E. Coils T and U also in the antenna and secondary circuits respectively, are so arranged-that the modulator rotator L passes through their field, but these auxiliary coils are not coupled to each other. Coils D and T in the antenna circuit are made equal to each other, as are also the coils F and U in the secondary circuit.

One mode of arranging and mounting the coils relative to the rotator L, is indicated in side view in Fig. 7. Coils D and F, as in Fig. 1, are mounted opposite each other, while coils T and U are mounted out of the field of each other and of coils D and F These auxiliary coils T and U are so laced that when a tooth R of the rotator lies squarely between coils D and F, air

spaces are directly opposite coils T and U, and vice versa.

As the inductance of coils D and F is diminished by the gradual introduction of a tooth R between them, the inductance of coils T and U is increased by an appreciable amount in exact synchronism therewith, because of the rigid connection between the various teeth of the rotator. The total inductance of coils D and T remains unchanged, as also'does the total on through a radio frequency amplifier of any suitable type, indicated diagrammatically at a, and thence to the modulator b after which it is detected (rectified). The modulator b is shown as comprising the coupling coils 0 and d coupling the output circuit (2 of the amplifier to the detector circuit E, which corresponds to the secondary circuit E in Fig. 1. The amplifier a is indicated merely as a box for simplicity and is marked in the drawing with the legend Radio frequency amplifier because it is thought unnecessary to complicate the drawing by showing the actual amplifier circuits, since any suitable known circuits and apparatus may be used. This applies also to the diagrammatic showing in Figs. 9, 10, and 11., in which the amplifiers are marked with appropriate legends indicating their location.

In Fig. 9 the antenna current passes through. a radio frequency amplifier f, thence through the modulator I), and thence through a radio frequency or audio frequency amplifier g as indicated to the detector and telephone circuit.

In Fig. 10, is shown a preferred form of apparatus which has been used in practice with highly satisfactory results. me the antenna current passes through an initial four-step radio frequency amplifier IL, thence through transformer j, thence through an intermediate three-step radio frequency amplifier k, to and through the modulator b, and through a final two-step audio frequency amplifier 0, finally reaching the detector and telephone circuit.

Fig. 11 shows another modification in which the antenna current, after rectifica tion, passes through a series of radio frequency amplifiers p to the modulator I), having the coils 0' and d wound on iron cores 0 and (P. The output of the radio frequency amplifier, consisting of radio frequency half waves is subject to modulation. From the modulator b, the current may pass to further amplifiers or the telephone receiver.

In Figs. 8, 9, 10, and 11, a series of units, as the amplifiers, modulators, and detectors, are each enclosed in a metal box as indicated, forming a grounded shield of highly conducting material. Preferably also all connecting leads are enclosed in grounded conducting shields as well. In this way undesired interaction between various circuits is avoided. The shielding of the units and the leads forms the subject matter of a separate application for patent of Julius lVeinberger, Serial No. 443,318, and these elements are not therefore shown in detail herein.

In a modification of the invention shown in Figs. 12 and 13, the coupling coils of the modulator are arranged in two sets V, X,

and W, Y, in both the primary and secondary circuits. The two primaries V and X,

In this figspaced an even number of tooth widths apart as shown in side view in Fig. 13 are connected in series with opposite direction of winding. The two similar secondaries \V and Y also differentially wound are connected in the secondary circuit E and arranged opposite the primaries V and X. Under theseconditions both primary-tosecondary couplings add their effects, but notwithstanding, for external fields, both primary and'secondary are non-inductive and therefore will not pick up motor noises.

The particular form of modulator or conpler and decoupler shown in Figs. 1 to 13 inclusive has a toothed conduct-ing rotator as an element by means of which intermittent coupling between the primary and secondary is secured. I am not to be understood however, as limiting the invention to this particular form of intermittently short circuited secondary adapted to be inserted and withdrawn between the primary and secondary of the coupler. Any equivalent device may be used, as shown in Figs. 1st and 15 in which a conducting shield in the form of a cylinder 9 having a serrated edge 1 is rotated between the coupling coils D and F. Fig. 15 is an end view of Fig. 14 showing the location of the .coils relative to the serrated edge of the shield.

In Fig. 16 a shield s is shown in the form of a fiat ring bent into wave form and adapted to be rotated between the coils D and F which are diagrammati -ally indicated as in Figs. 14 and 15 without the remainder of the circuits for simplicity.

Fig. 17 is a perspective view and Fig. 18 is an end view of a shield consisting of metallic segments 15 on the surface of a cylinder 0.

Fig. 19 shows a small short circuited sec ondary in the form of a ring or coil to, which may be tuned or untuned and is mounted to be rotated between the modulator coils D and F.

Fig. 20 shows a series of small tuned or untuned secondaries formed by a perforated disk at which is adapted to be rotated between the rodulator coils D and F, thus bringing the disk successively into coupling and decoupling position.

In Fig. 21 a stationary tuned or untuned short circuited secondary in the form of a ring or coil 3 is located between the coils D and F and adapted to be opened and closed by means of a suitable intermittent contact device 2.

I claim and desire to obtain by Letters Patent the following:

1. In radio signaling, the method of receiving sustained wave signals, which consists in intermittently shielding the secondary from the primary coils acting as a transformer in the receiver circuits, at a rate capable of modulating the incoming energy at an audible frequency thereby varying the coupling and producing an audio frequency in the receiver.

2. In radio signaling, the method of receiving sustained wave signals, which consists in intermittently electro-magnetically shielding the secondary from the primary of a transformer in the receiver circuits, at a rate capable of modulating the incoming energy at an audible frequency thereby producing an audio frequency in the receiver.

3. In apparatus for receiving sustained wave signals, the combination of receiving circuits, and means for modulating the incoming energy comprising coupling coils acting as a transformer in the receiver circuits and means for intermittently shielding the secondary from the primary coupling coil, at a rate capable of modulating the in coming energy at an audible frequency thereby varying the coupling and producing an au io frequency in the receiver circuits.

4:. In apparatus for receiving sustained wave signals, the combination of receiving circuits, and means for modulating the incoming energy comprising coupling coils acting as a transformer in the receiver circuits and means for intermittently electromagnetically shielding the secondary from the primary coupling coil, at a rate capable of modulating the incoming energy at an audible frequency thereby producing an audio frequency in the receiver.

5. In apparatus for receiving sustained wave signals, the combination of receiving circuits, and means for modulating the incoming energy comprising coupling coils acting as a transformer in the receiver circuits and means for intermittently interposing a conducting medium between the coupling coils, at an audio frequency.

6. In apparatus for receiving sustained wave signals, the combination of receiving circuits, and means for modulating the incoming energy comprising coupling coils acting as a transformer in the receiving circuits and means for intermittently interposing a short circuited secondary between the said coupling coils, at an audio frequency.

7. In apparatus for receiving sustained wave signals, the combination of receiving circuits, and means for modulating the incoming energy comprising coupling. coils acting as a transformer in the receiving circuits and means for periodically inserting and withdrawing a shield of conducting material between said coupling coils, at a frequency capable of producing an audible tone in the receiver circuits.

8. In apparatus for receiving sustained wave signals, the combination of receiving circuits, and means for modulating the incoming energy comprising coupling coils acting as a transformer in the receiving circuits and means for periodically varying the mutual in between said coupling coils at a rate capable of producing an audible tone in the receiver circuits, and means for maintaining the total inductance of the receiver circuits substantially constant, thereby preventing periodic detuning of said circuits.

9. In apparatus for receiving sustained wave signals, the combination of receiving circuits, and means for modulating the incoming energy comprising coupling coils acting as a transformer in the receiving circuits and means for periodically varying the mutual field of said coupling coils, and means for maintaining the total inductance of the receiver circuits substantially constant, thereby producing an audio frequency in the receiver circuits and maintaining the tuning of the circuits substantially constant.

10. In apparatus for receiving sustained 'Wave signals, the combination of receiving circuits, means for modulating the incoming energy comprising coupling coils acting as a transformer in the receiving circuits, a short circuited secondary, and means for interposing said short circuited secondary between said coupling coils at a rate capable of producing an audible tone in the receiver circuits, and means for maintaining the total inductance of the receiver circuits substantially constant, thereby preventing periodic detuning of said circuits.

11. In apparatus for receiving sustained wave signals, the combination of receiving circuits, means for modulating the incoming energy comprising coupling coils acting as a transformer in the receiving circuits, a con- .cuits'and releasing the incoming ener ducting medium, means for inter-posing the conducting medium between said coupling coils at a frequency capable of producing an audible tone, and means for maintaining the total inductance of the receiver circuits substantially constant, thereby producing an audible tone in the receiver circuits and maintaining the tuning of the circuits substantially constant.

12. In radio signaling, the method of tone reception for. sustained oscillations, which consists in alternately dissipating the incoming energy outside of the signaling circuits and releasing the incoming energy into the detecting circuits at a rate capable of roducing an audio frequency and an audiiile tone in the detector circuits.

13. In radio ap aratus for tone reception of sustained osci lations, the combination with an antenna,'of receiving circuits, and means for alternately dissipating the incoming energy outside of the signaling cirinto the receiving circuits at a rate capa le of producing an audio frequency and an audible tone in the receiver circuits.

14. In radio signaling, themethod of tone corresponding to that of an audible tone.

reception forsustained oscillations, which consists in alternately dissipating the incomin energy outside the signaling circuits and re easing the incoming energy into the detector circuits at a rate capable of producing an audio frequency and an audible tone in'the detector circuits and maintaining the tuning of the circuits substantially constant.

15. In radio apparatus for tone reception of sustained oscillations, the combination of receivin circuits, and means for alternately dissipating the-incoming energy outside the signaling circuits and releasing the incoming energy into the receiving circuits at a rate capable of producing an audio frequency and an audible tone in the receiver circuits, and means. for maintaining the impedance of the antenna and receiving circuits substantially constant.

16. In apparatus for receiving sustained wave signals, the combination of receiving circuits and coupling coils therein, of a member having a plurality of conducting projections movable through the mutual field of said coils at a frequency corresponding to that of an audibletone.

17. In apparatus for receiving sustained Wave signals, the combination of receiving circuits and coupling coils therein, of a member having a plurality of conducting projections, rotatable through the mutual field of said coils at a frequency corresponding to that of an audible tone.

18. In apparatus for receiving sustained wave signals, the combination of receiving 100 circuits and coupling coils therein, of a flat plate having a plurality of conducting projections movable through the mutual field of said coils at a frequency corresponding to that of an audible tone.

19. In apparatus for receiving sustained Wave signals, the combination of receiving circuits and coaxial cou ling coils therein, of a member having a p urality of conduct- I ing projections rotatable about an axis 110 parallel to the axis of the coils through the mutual field of said coils at a frequency corresponding to that of an audible tone.

20. In apparatus for receiving sustained Wave signals, the combination. of receiving 115 circuits and flat spiral coupling coils therein, and a flat plate having a plurality of conducting projections rotatable through the mutual field of said coils at a frequency 21; In apparatus for receiving sustained wave signals, the combination of receiving circuits and a pair of cou ling coils there-- in closely adjacent each ot er, and a memher having a plurality of conducting rojections movablethrough the mutual eld of said coils at a frequency corresponding to that of an audible tone.

22. In apparatus for receiving sustained wave signals, the combination of receiving 130 .flat conducting plate having a circuits, and a pair of flat coupling coils therein. closely adjacent each other and a lurality of teeth rotatable between the ooi s at a frequency corresponding to that of an audible tone.

' 23. In apparatus for receiving sustained wave signals, the combination of receiving circuits and couplin coils therein, and a member having a p urality of conducting project-ions movable between the coils, said coils and projections having areas of'similar magnitude.

2-1. In apparatus for receiving sustained wave signals. the combination of receiving circuits, and means for modulating the incoming energy comprising coupllng coils acting as a transformer in the receiver circuits and a grounded short circuited secondary adapted to be moved through the mutual field of said coils at a frequency corresponding to that of an audible tone.

25. In apparatus for receiving sustained wave signals, the combination of receiving circuits, coupling coils therein, an inductance coil in the antenna and an inductance coil in the receiving circuits, said inductances being in decoupled relation, and a member having a plurality of conducting projections adapted to be alternately interposed at a frequency corresponding to an audible tone in the mutual field of the coupling coils and in the self fields of the inductance coils.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses:

ALFRED NORTON GOLDSMITH. [1,. s.]

\Vitnesses CARL Dnmmn, ISABEL McCoMB'. 

